The aim of this study was to investigate the species composition of stomach nematodes in harbour seals, and determine if heart- and lung worms are present in the populations in the two areas Sandøy and Hvaler. The results from the study shows great variation in the composition and distribution of the three main species of stomach nematodes in harbour seals, and also revealed that there was nematodes both in the heart and lungs of some of the seals caught. However, no direct conclusions could be made regarding the composition of stomach nematodes; the low number of harbour seals investigated was the reason for this.
Nematodes from harbour seals in Hvaler (Østfold County) and Sandøy (Møre and Romsdal County), were analyzed. The nematodes were collected from the stomach, heart and lungs of the seals. A total of 156 nematodes were found, where four were from the lungs and one from the heart. The species found were Anisakis simplex, Pseudoterranova decipiens, Contracaecum osculatum, Otostrongylus circumlitus and Acanthocheilonema spirocauda. P. decipiens was the species with most representatives in this study with 77 nematodes, followed by 54 A. simplex and 20 C. osculatum. There were four O. circumlitus and one A. spirocauda.
There could not be detected any certain trend or pattern for the distribution of the nematode. Due to small sample size the dataset could not be distributed normally. Likewise, statistical significance in difference between the two areas or between the species could not be proven. Hvaler was the area with the highest amount of stomach nematodes with a mean of 38 nematodes. There were only two seals caught in that area. Fives seals were caught in Sandøy with a mean of 15 nematodes. Both the heartworm and the four lungworms were found in seals caught in Sandøy. Considering the economical and ecological importance nematodes in seals have, more emphasis should be put on the nematode faunal distribution and patterns in coastal management. More samples from seals along the coast of Norway could reveal a pattern and explain why the nematode abundance and diversity trends are so variable in harbour seals.